Presentation
Decreased visual acuity. The ophthalmological exam revealed a small black mass at the optic disc of the left eye.
Patient Data
Small lesion of the left optic nerve immediately posterior to the optic nerve head with no extension in the surrounding intraconal fat. It displays a high signal on T1, low signal on T2 and FLAIR with enhancement well-demonstrated on the subtraction images. Atrophy of the left optic nerve and optic chiasma.
Mild cerebral volume loss with small vessel ischemic changes are noted.
Annotated images showing the optic nerve lesion on the different sequences.
Case Discussion
MRI features of a small lesion of the left optic nerve of high signal on T1 and T1 fat sat and low signal on T2 and T2 fat sat, typical of melanocytoma on the ophthalmological exam with associated optochiasmatic atrophy.
Melanocytoma of the optic nerve head is considered as a benign lesion typically dark or dark brown pigmented lesion on the ophthalmological exam, usually located over or adjacent to the optic disc 1,2.
On imaging, the main differential diagnosis includes: malignant melanoma and juxtapapillary choroidal nevus. The malignant transformation is rarely described in literature 1,2.
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